The present invention relates to hinges, and in particular to a hinge including a self-closing feature.
Spring biased hinges are commonly used on refrigerator doors to bias them closed so that they do not accidentally remain ajar. However, many spring biased hinges build up an undesirably high biasing force when the doors are fully opened since the springs continue to compress as the doors open. This is undesirable since it tends to cause the doors to slam shut. Further, many consumers prefer that, once the refrigerator door is opened, the door stay open and/or swing freely so that the door does not interfere when the user is cleaning, accessing or restocking the refrigerator. Another problem is that many of the spring biased hinges have a bulky profile which tends to detract from the overall appearance of the refrigerator. Still further, most spring biased hinges include multiple parts which are more expensive to manufacture and assemble than is desirable.
Some refrigerator door hinge designs use an over-center spring arrangement wherein the spring provides a reduced biasing torque as the door is opened. This is because, in over-center springs, the direction of the spring force approaches the axis of rotation as the door is opened. Further, the over-center spring may provide a reverse biasing force to hold the door open once the spring passes over-center. U.S. Pat. No. 4,690,468 discloses such an arrangement. However, these over-center spring hinges typically do not provide a "bias free", zone of door movement, as is desired as noted above, and can actually cause the door to swing open and strike an appliance or counter top positioned adjacent the door. Further, in most of these hinges, the over-center spring passes through the axis of rotation as the door is opened, thus complicating the hinge pivoting arrangement and increasing the number of parts required. Also, the more complicated of these hinges have a bulky profile due to the size of the spring and the other components contained therein. Still further, often a different hinge bracket must be used for each different arrangement of doors, such as for right hand or left hand mounted doors, or for top and bottom mounted doors.
Camming arrangements are also sometimes used to accomplish the desired biasing of the door. Typically, a cam follower is biased into engagement with a cam as the door is opened, the cam being shaped to generate a closing force or to allow the door to swing freely, depending upon the door position. U.S. Pat. No. 4,215,449 discloses such an arrangement. However, the cam and cam follower take up vertical space and, hence, do not present a low profile. Further, camming arrangements generally tend to involve multiple parts and moving pieces that add to the complexity of the hinge design.
In one known camming arrangement, a beveled washer is installed around the door pivot, and as the door rides up the ramp, gravity generates a closing force on the door. However, while the arrangement has few parts, the vertical door movement causes door alignment problems.
Hence, an improved door hinge is desired.